Piston



Patented June 30, 1931 l UNITED STATES.

PATENT OFFICE STEPHEN D. EABTOG', 0F ST. LOUIS, MISSOURI, ASSIGNOR TOHARRY J. HATER, OF

, CINCINNATI, OHIO PISTON Application. filed December 18, 192-8. SerialNo. 326,832.

My invention relates to improvements in pistons, and more particularlyto pistons adapted for use in internal combustion ennes.

Better results are obtainedfrom internal combustion engines having lightweight reciprocating parts, such as the pistons, and the light weightmetals usually utilized for this purpose are aluminum, aluminum alloy,

magnesium and similar metals. These metals have properties which must beconsidered in the formation of pistons, namely, a relatively lowspecific gravity, a relatively high thermal conductivity, and acomparativel high 15 thermal expansion ratio. It is the o ject of thisinvention to produce a piston using these metals, in which the latterproperty 1s rendered comparatively ineffective for all practicalpurposes.

important object of this invention,

therefore, is the production of a piston so.

constructed that the heat `of combustion, which causes undesirableexpansion of the piston skirt is so diverted and impeded in the courseof its transmission fromthe head of the piston to its skirt, that itsinfluence upon the skirt of the piston is reduced to a minimum.

Another object of my invention is to produce a piston, both thrust facesof which will be in constant contact with the surface of the cylinderwalls.

Figure 1 is a front elevation of my im' proved piston,

Figure2 is a side elevation thereof, A Figure 3 is a vertical centralsectional View on the line 3-3 of Figure 1, Figure 4 is a transversesectional view takenA on the line 4-4 of Figure 2, and

circumferentially extending o ening 14.

The piston skirt is relieved by eing completely cutaway4 atdiametrically opposite points, and said cutaway port-ions 15 extend frompoints spaced from the bottom of the skirt to the opening 14. Amilo orstrut 16 is arranged centrally of each cutaway portion and connects t-hehead or rim 11 of the piston with the portion of the skirt forming thelower side of the cutaway portion 15. The

struts 16 are oiiset inwardly to avoid contact with the cylinder walls,and .are formed integrally with the head and skirt of the piston.

Piston pin receiving hubs or bosses 17 are integrallyuformed on thestruts 16 adjacent their centers, and are provided with the l'usualbores 18. These hubs preferably eX- tend inwardly be ond the struts 16,and while they may also extend outwardly beyond the struts, they mustclear the cylinder walls. Transverse struts 19 connect the hubs 17adjacent their inner ends, with the skirt 13 at the side edges of thecutaway portions 15. The struts 19 are arranged horizontally andfunction to resist the side thrust to which the piston is subjected whenin operation.

Reinforcing ribs 19 are arranged interiorly of the struts 19, on theupper and lower edges thereof, and increase in width from the boss 18 tothe piston skirt, as shown in Figures 4 and 5.

It will be seen, then, that the hubs 17 are joined at their outer endsto .the head and the lower portion of the skirt'by the substantiallyvertically extending struts 16, and

joined at their inner ends to the skirt by the transverse struts 19,which are arranged substantially horizontal. At a suitable positionbetween the struts 16 and 19 there is an opening`20 dividing the innerend of each hub from the outer end thereof, and said opening 20 may becutafter the piston is cast, but is preferably cast with the piston. Thehubs 17 are consequently separated by the opening 20 into spaced innerand outer portions, the inner portions being integrally connected withthe struts 19 and the outer portion of the hubs 17 being integrallyconnected with the struts 16 there being no direct connection betweenthe struts 16 and the struts 19, or between the separated portions ofthe hubs. The struts 16 and 19 are, therefore, independent of oneanother, and heat passing from the head 1() through the struts 16 willnot be conducted to the struts 19 and the adjoining skirt portions.

The non-thrust side of the piston skirt is provided with an inclinedslit 21 which extends in a generally vertical directionv from the bottomof the skirt to the opening 14 which separates the head from the skirt,and the thrust side of the skirt is unbroken. A substantially continuousannular bearing surface is, therefore, formed adjacent the bottom of theskirt and is unbroken except for the single slit 21 which is slightlyinclined from ythe vertical. While the slit 21 completely separates thenon-thrust side of the skirt, 'the arrangement of the transverse struts19 and the portions of the skirt below the openings 15 which are bracedby the struts 16, is sulicient to hold the separated parts of thenon-thrust side of the skirt in position.

The arrangement of the strengthening ribs 19 gives the necessaryrigidity to the separated portions of the skirt.

In the operation of my improved piston, the head portion is subjected todirect heat generated by the explosion of gases in the combustionchamber, and this heat is conducted away through the integrallyconnected struts 16 and through the surrounding metal of the cylinder.,The struts 16 are the only portions of the piston having direct orintegral connection with the head of the piston and the only path bywhich the heatvmay be conducted to the piston skirt. The heat is soreduced when it reaches the bottom of the skirt that very little istransmitted upwardly to the side Walls of the skirt, `and is, therefore,comparatively ineffective due to the long and circuitous route which itmust travel.

It will be noted that this construction results in the inner bossesoperating at a lower temperature than the outer bosses, as they areseparated from the head and receive heat from the head only through thestruts 16 and the lower portions of the skirt.

The slit- 21 is for the purpose of allowing for expansion, but does notmaterially weaken the skirt because of the arrangement of the transverseribbed struts 19 and the substantially c'ontinuous annular bearingsurface at the bottom of the skirt, said arrangement effectively bracingthe split portion of the skirt.

Referring to Figure 5 it will be seen that the under side of the pistonhead is provided with three spaced, substantially parallel ribs 22.These ribs extend down the inner sides `of the piston head to a pointadjacent the hub 18, and consequently strengthen the rib 16, as seen inF iofure 3, as Well as the head of the piston, and provide for balancedheat dissipation.

This invention is an improvement on the piston covered b my pendingapplication No. 227,705 filed ctober 21, 1927.-

While I have shown and described the preferred embodiment of myinvention it is to be understood that various changes in the size, shapeand arrangement of parts may bc resorted to without departing from thespirit of my invention or the scope of the subjoined claims.

Having thus described my invention, what I claim and desire to protectby Letters Patent is:

1. A piston comprising a head, skirt and piston pin hubs, eachl of saidhubs comprising spaced portions, one of said spaced portions of each hubbemg connected to the head and the lower portion of the skirt, and theother portion-of each hub being connected to the sides of the skirt,said skirt being separated by a slit inclined from the vertical on thenon-thrust side thereof.

2. A piston comprising a head, skirt and iston pin hubs, said hubs beingsplit wherey they are divided into spaced portions, one

of said portions of each hub being joined by a member with the head andskirt and the other portion of each of said hubs being joined by amember with the sides of said skirt, said skirt being separated on itsnonthrust side by a substantially vertical extending slit, the separatedportions of the skirt being braced by the joining members.

3. A piston comprising a head, skirt and piston pin hubs, membersjoining said hubs with the head and skirt, and members joining said hubswith the side portions of the skirt, said hubs being splitl between thejoinlng members whereby said joining members are independent of oneanother, and said skirt being separated; on its non-thrust side by aninclined slit, the separated portions gf the skirt being bracedfby thejoining memers.

4. A piston comprising a head, a skirt spaced from said head by acircumferentially extending opening, said skirt'being provided withdiametrically opposed cutaway portions, longitudinal struts connectingthe head with the portions of the skirt at the lower ends of the cutawayportions and arranged adjacent the centers o the cutaway portions,

piston comprising" a head, a 'skirt' spaced from the head and providedwith diametrically opposed cutaway portions extending from the top ofthe skirt to a. point spaced from the bottom thereof, whereby asubstantially continuous annular bearing surface is provided adjacentthe l,bottom of the skirt, a longitudinal strut extending across thecenter of each cutaway portion and integrally connecting the head withthe portion of the skirt arranged at the bottom of the cutaway portion,said strut having a piston pin hub integrally formed therewith andextending inwardly therefrom, a transverse strut integrally connectingthe inner end of each piston pin hub with the portions of the skirtadjacent the side edges. of the cutaway portions, the hubs being splitbetween the longitudinal and transverse struts whereby the struts areeach divided into spaced portions, the` outer portion being connected tothe longitudinal strut and the inner portion being connected to thetransverse strut, the skirt being provided on its non-thrust side withan inclined slit extending from the bottom of the skirt to the s acebetween the head and skirt, the separated) portions of the skirt `beingbraced by the portions Pof the skirt below the cutaway portions, and bythe 1ongitudinal and transverse struts.

6. A piston comprising a head, skirt and piston pin hubs, membersjoining said head and skirt, and members joining said hubs with the sideportions of the skirt, said last mentioned members having reinforcingribs extending from a point adjacent the hubs to the piston skirt, saidhubs being split between 1the joining members whereby said joiningmembers are independent of one another, and said skirt being separatedon its non-thrust side by an inclined slit, the separated portions ofthe skirt being braced by the joining members and strengthening ribs.

7 A piston comprising a head, skirt and piston pin hubs, struts oiningsaid hubs with the head and skirt, struts joining said hubs with theside portions of the skirt, and reinforcin ribs on said last-mentionedstruts, said ri s increasing in width from the hubs to the piston skirt,and said hubs being split between the joining struts, whereby saidstruts are independent of one another.

.8. A iston-comprisin la head, a skirt separated rom said. head, pistonpin hubs, members joining said hubs with the head and skirt, and membersjoining said hubs with the side portions -of the skirt, said hubs beingsplit between the joining members whereby said joining members areindependent of o ne another, and said skirtv being separated on itsnon-thrust side by an inclined slit, the separated portions of the skirtbeing braced and held in position by the last named joining members. j

9. A piston comprising a head, a skirt spaced from said head, piston pinhubs, struts joining said hubs with the head and skirt, and struts joining` the hubs with the side portions of the skirt.,y said hubs beingsplit between the struts whereby said struts are 1ndependent of oneanother and the first named struts are the only connection between thehead and skirt, and said skirt being separated on its non-thrust side byan inclined slit, the separted portions of the skirt being braced andheld in position by the last named struts. In testimony whereof I affixmy signature.

STEPHEN D. HARTOG.

